Basic HTML version of Foils prepared Nov 29 97

Foil 34 Logical Time

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. by Geoffrey Fox but selected by W. Furmanski from DMSO
Classical discrete event simulation programs process all events in time stamp order
A mechanism is required to enable federates to interleave processing of local events with those received from other federates
Logical time (applicable to coordinated time advance federates):
  • If the logical time of a federate is T, the RTI guarantees no more TSO messages will be passed to the federate with time stamp < T
  • Local events with time stamp < T can be "safely" processed
  • Logical time in a federate only advances when that federate explicitly requests an advance:
    • Time Advance Request (T): requests advance to time T
    • Next Event Request (T): requests advance to time stamp of next TSO message, or T, which ever is smaller
    • RTI issues Time Advance Grant (T') when logical time advanced to T'
  • Federates responsible for pacing logical time advances with wallclock time in (scaled) real-time executions

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